1. Field of the Invention
The invention concerns a device and a method for data transfer between a rotatable part and a stationary part of a gantry of a computed tomography apparatus. The invention moreover concerns a computed tomography apparatus that embodies such a device for data transfer.
2. Description of the Prior Art
A computed tomography apparatus, in particular an x-ray computed tomography apparatus, has a gantry with a part that can rotate relative to a stationary part, on which rotatable part are arranged (among other things) an x-ray source and an x-ray detector opposite one another. In operation of the x-ray computed tomography apparatus, large quantities of measurement data accumulate due to the acquisition of numerous x-ray projections. This measurement data must be transferred from the rotating part of the gantry to the stationary part, since the processing of the measurement data (in particular the reconstruction of slice images and 3D images based on the measurement data) ensues with an image computer located at the stationary side.
Furthermore, in operation of the x-ray computed tomography apparatus, bidirectional operating data of the x-ray computed tomography apparatus (such as control data, status data etc.) must be transferred from the stationary part to the rotatable part of the gantry and from the rotatable part to the stationary part.
The data transfer between the stationary part of the gantry and the rotatable portion of the gantry can occur by mechanical contact by means of slip rings or without contact, for example by means of capacitive coupling. For example, in DE 10 2005 056 049 A1 a contactless data transfer by means of capacitive coupling in a computed tomography apparatus is described. At least one strip conductor (stripline) pair for symmetrical data transfer is mounted on the rotatable part of the gantry, into which conductor pair the data to be transferred, or electrical signals carrying the information, are fed by a transmission module. At least one receiver element is mounted on the stationary part. This receiver element is located along at least one segment of the strip conductor pair during the relative movement of the two parts with slight separation and is connected with a receiver module.
A computed tomography apparatus normally has multiple such data transfer (transmission) links, each having a strip conductor pair. A first data transmission link is present for the transfer of the measurement data acquired with the x-ray detector from the rotatable part to the stationary part of the gantry. A second data transmission link is provided for the transfer of operating data of the computed tomography apparatus from the stationary part to the rotatable part of the gantry, and a third data transmission link is provided for the transfer of operating data of the computed tomography apparatus from the rotatable part of the gantry to the stationary part. The second and third data transmission links serve for the generation of the redundancy necessary for the transfer of operating data in order to achieve a certain data transfer rate between the rotatable part of the gantry and the stationary part.
The provision and the parallel operation of the three transmission links for data represent a not inconsiderable technical and financial cost.